LAUSR

The concept of reactivity and stability ratings is proposed as a screening tool for identification of reactive and stable catalysts in the dry reforming reaction of methane (DRR), in which reactivity and stability against coking are the largest concerns. The rating concept links the activation energy (Ea) of selected sets of elementary steps corresponding to DRR reactivity and stability for a particular catalyst with respect to the Ni(111) reference catalyst. This is done by transforming the Ea into reactivity rating (RT-R) and stability rating (RT-S) by applying a rating scale. A specific rating scale is defined in order for any system to be compared using the indexes on the reactivity surface (RS) and stability surface (SS). RS and SS were constructed as functions of RT-R and RT-S to illustrate reaction and coking schemes, together with the rate of reaction and coking at any value of these rating indexes. Hence, the concept could evaluate the catalyst qualitatively and quantitatively. Moreover, guidelines to achieve reactive-stable catalysts are proposed from the analysis of the RS and SS indexes, along with the application of the rating concept not only for describing the reactivity and stability of the Ni–Ni3C–NiO catalyst system during DRR, but also to suggest what compositions of each phase would yield high reactivity and stability of the system.